Happens to all of us. Someone says something and our whole day is ruined, or maybe even the whole week, if not longer. I think this is a good mantra to keep repeating in order to stay focused on what’s truly important.
P.S. This doesn’t apply to children, because if they make you angry by just being kids you need to seriously start researching positive/conscious/peaceful parenting alternatives. Adults getting angry at children has nothing to do with children, but with adults’ unresolved issues in their past.